A study of isolated contractions of the longitudinal muscle layer of the duodenum has been completed. The results indicate that isolated contractions of the longitudinal muscle layer occur in synchrony with the electrical slow waves, with shortening of the contracted segment to about 40% of resting length. A hypothesis about their effect upon flow of intraluminal contents was tested in a model and analyzed mathematically. It is suggested that such contractions induce circulation from the core of the lumen to the periphery. Net aborad flow in the small bowel was examined in rats and dogs to investigate the effects of the polypeptide enteric hormones and the effect of the pattern of contractions on flow. These confirm hypotheses about the relationships of contracts to net aborad flow. The last year of this grant will be spent completing preparation of a large body of data for publications, data dealing with the configuration and distribution of ring contractions in the duodenum.